Operating systems
⏱ ~3-min readAceMark Guide
What this topic is really about
A blocked process cannot proceed because it is waiting for an external event such as I/O completion or the availability of a needed resource; the operating system places it in the blocked queue until the event occurs. Confusing this with waiting for CPU time is a typical error—processes ready for CPU are in the ready state, not blocked.
Virtual memory maps a program's virtual addresses to physical memory or secondary storage, allowing programs to execute even if they exceed physical RAM capacity. It does not make programs run faster than physical memory (Option A); in fact, swapping pages to disk introduces latency that slows down execution.
See the mechanism
Deadlock prevention requires violating at least one of Coffman's four necessary conditions, such as eliminating the hold-and-wait condition by forcing processes to request all resources at once. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.
An exam-style question, fully explained
Deadlock can be prevented by:
- Identify what the question tests: Deadlock can be prevented by:.
- Deadlock prevention requires violating at least one of Coffman's four necessary conditions, such as eliminating the hold-and-wait condition by forcing processes to request all resources at once.
- Relying solely on resource preemption is a recovery or avoidance strategy rather than a strict prevention method.
Traps the examiner sets
- Read each option carefully — distractors on Operating systems are designed to look plausible.
- Re-check the exact wording of the question stem before committing to an answer.
- Watch the qualifiers ("always", "only", "except") that flip a correct-looking option.
Test your recall
Answer each from memory — you'll see instantly whether you're right and why.
Run a focused 10-question mini-mock on Operating systems and see it stick.
Practice more of this topic →